1. Field of the Invention
The present invention relates to an end-side member used in an image forming apparatus such as a laser printer or a copy machine, and a photoreceptor drum unit and a process cartridge provided with the end-side member.
2. Description of the Related Art
An image forming apparatus such as a laser printer or a copy machine includes a process cartridge detachably provided at a body of the image forming apparatus (hereinafter, also referred to as an “apparatus body”).
The process cartridge is a member which forms content of print, such as characters or drawings, while being attached to the apparatus body and transforms the content to a recording medium such as a paper. Therefore, the process cartridge is provided with a photoreceptor drum on which content to be transferred is formed and a charging tool and a developing tool for forming the content to be transferred to the photoreceptor drum.
In relation to the process cartridge, the same process cartridge is attached to or detached from the apparatus body for maintenance, or an old process cartridge is detached from the apparatus body and a new process cartridge is attached to the apparatus body to replace the old process cartridge with the new process cartridge. It is desirable that a user of the image forming apparatus can do such attachment and detachment of the process cartridge by themselves, and in that regards, it is desirable that such attachment and detachment of the process cartridge is easy to do.
In addition, the rotation of the photoreceptor drum included in the process cartridge when the photoreceptor drum is operated is necessary. Thus, the photoreceptor drum is provided with a bearing member such that a drive shaft of the apparatus body is engaged therewith in a direct manner or via another member and the photoreceptor drum receives rotation force from the drive shaft and rotates.
In contrast, it is necessary to release (separate) the engagement between the drive shaft of the apparatus body and the bearing member provided at the photoreceptor drum and reengage the drive shaft and the bearing member every time in order for the process cartridge to be attached to and detached from the apparatus body as described above.
JP-A-8-328449 and JP-A-10-153941 disclose techniques of providing a drive shaft moving in an axial direction on the apparatus body side, forming a twisted hole with a polygonal cross-sectional shape at the drive shaft, and providing, as a bearing member, a projection with a polygonal columnar shape which is inserted into the twisted hole at the drive shaft for delivering drive force. The projection disclosed in JP-A-8-328449 has a twisted columnar shape corresponding to the twisted hole at the drive shaft. In contrast, the projection disclosed in JP-A-10-153941 has a non-twisted columnar shape.
An object of both the techniques disclosed in JP-A-8-328449 and JP-A-10-153941 is to enhance rotation accuracy of the photoreceptor drum and to reliably deliver the drive force from the apparatus body to the photoreceptor drum.